Anchoring element for a hydraulic engineering installation

ABSTRACT

The invention relates to an anchoring element for a hydraulic engineering installation having at least one ballast weight for weighting purposes and is characterized in that the anchoring element comprises a plurality of shear-protection elements which are arranged movably on lateral guides in the anchoring element such that, when the anchoring element is deposited on the bottom of a body of water, the shear-protection elements bear down on the bottom of the body of water under their own weight when in contact with said bottom and move individually along the respective lateral guide until the anchoring element assumes a position of equilibrium.

The invention relates to an anchoring element for a hydraulic-engineering installation, in particular a mooring block or a gravity foundation for an offshore power generating plant or a centring and guidance aid for a monopile foundation and a drilling on the bottom of a body of water.

In order to form a permanent anchoring point on the bottom of a body of water, typically a weight is sunk from which a connecting chain is guided to an anchoring buoy. On this matter, reference is made for example to US 2008/0112759 A1. Mesh baskets filled with broken rock, placed on the bottom of a body of water are deduced from this document. As an alternative, it is possible to form mooring blocks in the form of standardised concrete parts. In this case, a mooring block must have a high weight in order to serve as a secure anchoring point. In order to form anchoring elements for offshore installations, this results in the need to use special installation ships having a sufficient crane capacity in order to be able to place heavy anchoring elements.

In order to improve the durability of mooring blocks, JP 61046791 A suggested using spikes on the bottom of a mooring block which dig into the bottom of the body of water. This approach assumes a relatively soft sediment on the bottom of the body of water. Placing such a mooring block on rocky bottom surface can lead to a reduced anchoring effect. In order to provide sufficient safety margins, the weight of such anchoring elements is therefore increased, which however makes installation work difficult.

Reference is made to DE 10 2005 006 988 A1, for example, for the erection of wind power plants in marine locations. Furthermore, corresponding foundations secured by their own weight are known for completely immersed installations for obtaining energy from tides. In this case, a stony bottom surface results in particularly heavy foundation elements in order to be able to reliably eliminate any displacement of the installation by wave and flow forces.

If a pile foundation (monopile) is used as an alternative to a gravity foundation for the foundations of installations where the body of water has a rocky bottom, anchoring elements are used for centring the drilling to be performed for the pile foundation and for securing the immediate base region of the foundation—on this matter reference is made to EP 1 988 219 A1. For this application also heavy anchoring elements are placed on the bottom of the body of water.

GB 1 492 562 A further discloses a pile foundation for an oil platform for which a foundation element is initially placed on the bottom of the body of water and then secured by pressing in piles which extend from the foundation element. The piles are extended by means of a rear-side pressurisation by pumping in seawater into a sealed receiving chamber for the piles. After extending, the receiving chamber is filled with sand.

It is the object of the invention to provide an anchoring element for a hydraulic engineering installation that bears down on the bottom of a body of water through its own weight, where the ballast weight used is small compared to the limiting loads for shear protection so that it can be installed with a simplified ship. In this case, the anchoring element should in particular be suitable for stony and rocky bottom surface and should be characterised by a long lifetime and by constructive and production-engineering simplicity.

The object forming the basis of the invention is solved by the features of the independent claim. Advantageous embodiments are obtained from the subclaims.

In order to improve known anchoring elements which use a loading weight for securing, the inventors have identified that shear-protection elements which are arranged movably in lateral guides in the anchoring element, which become wedged in the unevenness of the bottom surface after placement on the bottom of the body of water substantially improve the load-bearing capacity of the anchoring element with respect to transverse forces. The shear-protection elements used for this purpose only move as a result of their own weight. Accordingly the lateral guides transmit shear forces but leave each individual one of the shear-protection elements a translational degree of freedom so that the shear-protection elements can be extended until they come in contact with the bottom of the body of water without an additional actuator mechanism.

Each of the shear-protection elements will occupy a specific equilibrium position when the anchoring element is placed on the bottom of the body of water. High loads on the anchoring element, in particular transverse forces, can lead to movement of the entire anchoring element without the individual contact points of the anchoring elements on the bottom of the body of water being substantially altered, i.e., the anchoring element as it were clings in the relief of the bottom surface with the freely movably extendable shear-protection elements.

In the simplest case, the shear-protection elements are applied positively to recesses in the body of the anchoring element so that the walls of the recesses form the lateral guides for the shear-protection elements. For a preferred configuration the recesses are configured as through openings in the anchoring element so that the shear-protection elements can be inserted from above into the through openings and comprise a suitable device for prevention of falling out, for example, in the form a cross-section widened in a flange shape in the head region. When lowering the anchoring element, the shear-protection elements are then held by the devices for prevention of falling out and at the same time project beyond the base region of the anchoring element. Upon contact with the ground, the shear-protection elements then bear down under their own weight on the bottom of the body of water and drive in so far until the entire anchoring element reaches its respective equilibrium position.

For an advantageous configuration the lateral guides in the contact region to the shear-protection elements are configured in the form of seawater-resistant friction bearings. For this purpose, the lateral guides themselves and/or the parts of the shear-protection elements coming in contact with the lateral guides are covered with a suitable friction bearing material. In particular, the material combinations known from the application for stern tubes come into consideration here. A hard-soft pairing has proved to be particularly durable. That is, one of the contact surfaces is covered with a highly loadable polymer, for example Orkot® whilst the counter running surface consists of a hard material, possibly of stainless steel. As a result of shear-protection elements formed in such a manner, the substantial part of the anchoring element and of the shear-protection elements can be made of a concrete material. For reasons of strength, fibre-reinforced concrete particularly comes into consideration here. A direct alternating sliding of the concrete components is avoided by the aforesaid measure. The wall of the receptacles in the anchoring element can thus be covered with the said friction bearing material whilst the shear-protection elements are configured in the form of steel tubes which are grouted with concrete to increase their own weight.

For an alternative configuration the lateral guides for the shear-protection elements in the form of spaced-apart plates, for example, made of steel are provided with through openings through which the shear-protection elements are guided. Particularly advantageously the shear-protection elements are provided with different cross-sections which are adapted to the dimensioning of the through openings so that the shear-protection elements are secured from falling out.

For a further alternative embodiment, the shear-protection elements lie directly adjacent to one another and have positive contact surfaces which are used to achieve the lateral guides and allow an alternate sliding of respectively adjacent shear-protection elements in the direction of translation provided for free movement. For such a configuration it is in particular feasible to configure the shear-protection elements as cuboids having the same dimensions which are bordered by a frame-shaped element that guides the shear-protection elements laterally towards one another. The arrangement is supplemented by a device for prevention of falling out.

The anchoring element according to the invention for a first configuration can stand on at least three shear-protection elements when placed on the bottom of a body of water. The remaining elements are freely movable, that is they are not guided to an end stop and therefore do not receive the weight of the anchoring element. However, as a result of their own weight they press on an associated contact point on the bottom of the body of water and absorb the transverse forces acting on the anchoring element via the respective lateral guide.

Alternatively, it is possible to support the anchoring element on another separate component. In the simplest case this is the load-absorbing frame of the anchoring element itself. For a further embodiment, the vertical loads are intercepted at contact points at which lifting devices are provided for levelling the anchoring element. Such a configuration can in particular be used to achieve a gravity foundation with an anchoring element according to the invention for the foundation of an offshore power generating plant. Accordingly, a centring and guidance aid for securing a drilling on the bottom of the body of water or for erecting a monopile foundation can be achieved by means of the anchoring element according to the invention.

The invention is explained in detail hereinafter with reference to exemplary embodiment in connections with the diagrams in which the following is shown in detail:

FIGS. 1 a and 1 b show a cross-sectional view of an anchoring element according to the invention before and after placement on the bottom of the body of water.

FIGS. 2 a and 2 b show an embodiment of the anchoring element according to the invention in a diagram according to FIGS. 1 a and 1 b.

FIGS. 3 a and 3 b show another alternatively configured anchoring element in cross-section before and after placement.

FIG. 4 shows a gravity foundation for an offshore power generating installation with an anchoring element according to the invention in partial sectional view.

FIG. 5 shows a centring and guidance aid for a monopile foundation with an anchoring element according to the invention in a cross-sectional view.

FIG. 1 a shows in cross-sectional view an anchoring element 1 according to the invention that comprises a rectangular concrete block 11 as ballast weight 2. The lowering on a chain 10 which is held on the lateral fastening elements 9.1, 9.2 is shown. An anchoring element configured in such a manner preferably serves as a mooring block.

Recesses 4.1-4.11 for receiving shear-protection elements 3.1-3.11 are provided in the concrete block 11 which is preferably configured to receive high loads made of fibre-reinforced concrete. The recesses 4.1-4.11 are preferably arranged in a matrix shape and provided for the present configuration in the form of through openings which extend from the upper side 38 of the concrete block to the base region 39. The longitudinal axes of the recesses 4.1-4.11 here run substantially vertically to the bottom region 39 provided as standing surface. Alternatively a certain angle of inclination is feasible which is preferably selected to be so steep and preferably <45° and particularly preferably <20° so that the shear-protection elements 3.1-3.11 overcome the frictional forces in the lateral guides and as a result of their own weight extend from the recesses 4.1-4.11 in the orientation provided for the lowering.

In the present case, the shear-protection elements 3.1-3.11 are designed to be cylindrical and tapered. Furthermore, in the top region they have a stop 7 which is designed in the form of a collar over dimensioned with respect to the cross-section of the recesses 4.1-4.11 and forms a device which prevents against falling out.

In each case, the walls of the recesses 4.1-4.11 which are designed as a form fit to the lateral surface of the shear-protection elements 3.1-3.11 serve as lateral guides 5 for the shear-protection elements 3.1-3.11.

In addition, the walls 12 are preferably covered with a friction bearing material 6. This is shown as an example by means of the recesses 4.1 for the shear-protection element 3.1. The friction bearing material 6 is used to reduce the frictional forces between the lateral guide 5 and the shear-protection elements 3.1-3.11 to such an extent that the own weight of the shear-protection elements 3.1-3.11 is sufficient for extending from the recesses 4.1-4.11. In addition, under continuous movement of the anchoring element 1 under changing inflow conditions or as a result of wave movements, the abrasion on the shear-protection elements 3.1-3.11 or on the walls 12 of the recesses 4.1-4.11 should be reduced.

FIG. 1 b shows the situation after placement of the anchoring element 1 on the bottom of the body of water 8. In this case, the concrete block 11 rests on the contact points 37.1, 37.2 on the bottom of the body of water 8. In general, at least three contact points will be provided which is not shown in the schematically simplified cross-sectional view.

For the present exemplary embodiment the anchoring element 1 is not supported directly on the shear-protection elements 3.1-3.11. However these are either in contact with the bottom of the body of water 8 or are located in an end position and are held by the device to prevent falling out. The last-mentioned case applies to the shear-protection element 3.6. The other shear-protection elements 3.1-3.5, 3.8-3.11 bear with their own weight on the bottom of the body of water 8 and adopt an individual position depending on the distance between the base region 29 of the concrete block 11 and the bottom of the body of water 8. They thereby follow the profile of the bottom of the body of water 8 and engage in indentations so that the forces acting on the anchoring element 1 do not lead to a displacement of the contact points. It is merely possible that the concrete block 11 executes a nodding movement under large shear forces, which leads to a certain movement of the shear-protection elements 3.1-3.11 along the associated lateral guides 5 without the contact of the shear-protection elements 3.1-3.11 on the bottom of the body of water 8 itself being lost.

FIGS. 2 a and 2 b show an alternative embodiment of the anchoring element 1 in cross-sectional view before and after placement on the bottom of the body of water 8. The schematically depicted shear-protection elements 3.1-3.7 are held in through openings in a first guide plate 13 and a second guide plate 15 which are parallel and spaced apart from one another to form the lateral guide 5. The first guide plate 13 and the second guide plate 15 are laterally cast into the concrete blocks 11.1, 11.2 which form the substantial part of the loading weight 2. The arrangement is covered by a cover plate 20 which is formed from a corrosion-resistant, sufficiently solid material in correspondence with the first guide plate 13 and the second guide plate 15. For example, these components can be designed as steel plates or as components made of fibre-reinforced concrete.

For the shear-protection element 3.1, as an example a lower through opening 14 is provided in the first guide plate 13 and an upper through opening 16 in alignment thereto in the second guide plate 15. As a result, the shear-protection element 3.1 is guided laterally at a steep angle preferably <20° and particularly preferably substantially perpendicularly to the placement direction. The narrower lower cylinder cross-section 17 of the shear-protection elements 3.1-3.11 reaches through the lower through opening 14. However, this is too narrow for the expanded upper cylinder section 18, thus achieving a device which prevents falling out 36. The upper cylinder section 18 passes through the wider upper through opening 16 and for the fully extended rest position of the shear-protection elements 3.1-3.11 shown in FIG. 2 a, extends beyond the second guide plate 15. The projecting part forming a head 19 is rounded so that when the shear-protection elements 3.1-3.11 are fully inserted, a gentle sliding of the head 19 on the inner side of the cover plate 20 located thereabove is ensured.

FIG. 2 b shows the situation of the anchoring element 1 from FIG. 2 a placed on the bottom of the body of water 8. It can be seen that the shear-protection elements 3.1 and 3.6 absorb the vertical loads of the anchoring element 1. The associated contact points 37.1, 37.2 are shown. A third contact point required for secure standing is not shown in the simplified cross-sectional view. The load-absorbing shear-protection elements 3.1 and 3.6 then each lie in the region of their head 19 on the inner side on the cover plate 20. Lateral forces are introduced at the lower through opening 14 in the first guide plate 13 and the upper through opening 16 in the second guide plate 15. In the case shown, the further shear-protection elements 3.2, 3.3, 3.5, 3.7 bear down on the bottom of the body of water 8 with their own weight and impart retaining forces via the respective lateral guides 5 in the case of a transverse movement of the anchoring element 1.

FIGS. 3 a and 3 b sketch a further exemplary embodiment of the invention. Here the concrete blocks 11.1, 11.2 and the cover plate 20 form a part of a frame 40 which is closed towards the top for the precisely fitting shear-protection elements 3.1-3.6. These are designed so that each individual shear-protection element 3.1-3.6 has a contact surface 21.1, 21.2, 21.3 to an adjacent element which enables a positive sliding in the direction provided for the extension, in the present case the vertical. For the embodiment shown the shear-protection elements 3.1-3.6 are selected as rectangular concrete blocks. These can be covered with a friction bearing material for protection from abrasion, which however is not shown in the sketch in the figures. The individual shear-protection elements 3.1-3.6 held initially by means of a device for preventing falling out 36 on the cover plate 20 retract upon contact with the ground after placement of the anchoring element 1 on the bottom of the body of water 8 depending on the unevenness present on site. It can be seen that the shear-protection elements 3.1 and 3.5 are guided directly as far as the cover plate 20 and in consequence support the anchoring element 1 in a bearing manner. The other shear-protection elements 3.2-3.4 and 3.6 are located in an intermediate position where each individual one bears down on the bottom of the body of water 8 with its own weight and the relative position required for this to the respectively adjacent shear-protection elements 3.1-3.6 is accomplished by sliding along the contact surfaces 21.1-21.3. As a result, the topology of the ground contact points of the shear-protection elements 3.1-3.6 is adapted to the bottom of the body of water 8 with which shear forces on the anchoring element 1 can be reliably intercepted via the lateral guide 5.

FIG. 4 shows a further development of the invention in the form of a gravity foundation 22 for an offshore power generating plant, on which a wind turbine or, as shown in the present case, a tidal turbine can be placed. The figure shows a turbine chassis 27 with a water turbine 28 revolving thereon and an adjoining tower adapter 26 which can be placed on the coupling element 25 on the foundation-side support structure 24.

According to the invention, the gravity foundation 22 comprises an anchoring element 1 with shear-protection elements 3.1-3.8 arranged vertically movably in recesses 4.1-4.8. These retract when the gravity foundation 22 is placed on the bottom of the body of water 8 whilst maintaining contact with the bottom and thus form the adapted bottom region 39 of the gravity foundation 22.

The gravity foundation is levelled by the lifting devices 23.1 and 23.3 which support the weight force of the gravity foundation 22. Accordingly the freely vertically movable shear-protection elements 3.1-3.8 intercept a substantial part of the transverse forces acting on the gravity foundation 22 during operation of the installation.

For a further alternative embodiment, the stability of the gravity foundation 22 can be increased by supplying a cement mixture to a further construction step via a feed channel 35 for filling cavities. For this embodiment the shear-protection elements 3.1-3.8 are used for the initial securing during installation until the cement mass is finally hardened.

FIG. 5 shows a centring and guidance aid 30 for a drilling, possibly to form a monopile foundation. A foundation element comprising a concrete block 11 which serves as ballast weight 2 and at the same time as supporting component is again shown. According to the invention, the shear-protection elements 3.1-3.8 arranged on the concrete block 11 are placed freely movably vertically by means of their own weight in the recesses 4.1-4.8. These are again used for adaptation to the course of the bottom of the body of water 8. After the levelling by the lifting devices 23.1, 23.2, a drill pipe 32 with the drill head 33 can be lowered through the guide pipe 31 into a drill hole 34.

Further embodiments of the invention are obtained from the following protective claims. In particular, it is feasible to design the lateral guides 5 for the shear-protection elements 3.1-3.11 so that these extend in an angular position to the direction of placement. It is further possible to divide the shear-protection elements 3.1-3.11 into different groups which differ due to their direction of extension and through their weight or their extension length or in relation to the shape of the contact region to the bottom of the body of water. Furthermore, the entire outer surface of the anchoring element 1 can be covered with shear-protection elements 3.1-3.11 where only a part of the shear-protection elements 3.1-3.11 comes in contact with the bottom of the body of water 8 depending on the direction of placement. As a result, the anchoring element 1 can be placed on the bottom of the body of water 8 independent of direction, thereby simplifying installation.

REFERENCE LIST

-   1 Anchoring element -   2 Ballast weight -   3.1-3.11 Shear-protection element -   4.1-4.11 Recess -   5 Lateral guide -   6 Friction bearing material -   7 Stop -   8 Bottom of the body of water -   9.1, 9.2 Fastening element -   10 Chain -   11, 11.1, 11.2 Concrete block -   12 Wall -   13 First guide plate -   14 Lower through opening -   15 Second guide plate -   16 Upper through opening -   17 Lower cylinder section -   18 Upper cylinder section -   19 Head -   20 Cover plate -   21.1, 21.2 -   22.3 Contact surface -   22 Gravity foundation -   23.1, 23.2 Lifting device -   24 Supporting structure -   25 Coupling element -   26 Tower adapter -   27 Turbine chassis -   28 Water turbine -   29 Offshore power generating plant -   30 Centring and guidance aid -   31 Guide pipe -   32 Drill pipe -   33 Drill head -   34 Drill hole -   35 Feed channel -   36.1-36.6 Device for preventing falling out -   37.1, 37.2 Contact point -   38 Upper side -   39 Bottom region -   40 Frame 

1-8. (canceled)
 9. An anchoring element for a hydraulic engineering installation having at least one ballast weight for weighting purposes, wherein the ballast weight comprises a bottom region, characterized in that the anchoring element comprises a plurality of shear-protection elements which are arranged retractably freely movably on lateral guides in the anchoring element such that, before the anchoring element is deposited on the bottom of a body of water, the shear-protection elements project beyond the bottom region and are held by devices to prevent falling out, wherein the shear-protection elements bear down on the bottom of the body of water merely under their own weight when in contact with said bottom and retract individually along the respective lateral guide until the anchoring element assumes a position of equilibrium.
 10. The anchoring element according to claim 9, characterized in that each of the shear-protection elements is arranged inside a recess in the anchoring element and the walls of the recesses form the lateral guides.
 11. The anchoring element according to claim 9, characterized in that the lateral guides and/or parts of the shear-protection elements coming into contact with the lateral guides are covered with a friction bearing material.
 12. The anchoring element according to claim 9, characterized in that at least one part of the shear-protection elements is in direct lateral contact to one another, where the individual shear-protection elements can slide on one another and the lateral guide is effected by the alternate contact surfaces of adjoining shear-protection elements adjacent to one another.
 13. The anchoring element according to claim 9, characterized in that the shear-protection elements are secured against falling out from the anchoring element.
 14. The anchoring element according to claim 9, characterized in that the anchoring element is at least partially fabricated from fibre reinforced concrete.
 15. The anchoring element according to claim 9, characterized in that the anchoring element comprises a lifting device for levelling after placement on the bottom of the body of water.
 16. A hydraulic engineering installation having an anchoring element according to claim 9, wherein the hydraulic engineering installation serves as a gravity foundation for an offshore power generating plant or as a mooring block or as a centering and guidance aid for erecting a monopile foundation or for a drilling on the bottom of a body of water.
 17. The anchoring element according to claim 10, characterized in that the lateral guides and/or parts of the shear-protection elements coming into contact with the lateral guides are covered with a friction bearing material.
 18. The anchoring element according to claim 10, characterized in that at least one part of the shear-protection elements is in direct lateral contact to one another, where the individual shear-protection elements can slide on one another and the lateral guide is effected by the alternate contact surfaces of adjoining shear-protection elements adjacent to one another.
 19. The anchoring element according to claim 11, characterized in that at least one part of the shear-protection elements is in direct lateral contact to one another, where the individual shear-protection elements can slide on one another and the lateral guide is effected by the alternate contact surfaces of adjoining shear-protection elements adjacent to one another.
 20. The anchoring element according to claim 10, characterized in that the shear-protection elements are secured against falling out from the anchoring element.
 21. The anchoring element according to claim 11, characterized in that the shear-protection elements are secured against falling out from the anchoring element.
 22. The anchoring element according to claim 12, characterized in that the shear-protection elements are secured against falling out from the anchoring element.
 23. The anchoring element according to claim 10, characterized in that the anchoring element is at least partially fabricated from fibre reinforced concrete.
 24. The anchoring element according to claim 11, characterized in that the anchoring element is at least partially fabricated from fibre reinforced concrete.
 25. The anchoring element according to claim 12, characterized in that the anchoring element is at least partially fabricated from fibre reinforced concrete.
 26. The anchoring element according to claim 13, characterized in that the anchoring element is at least partially fabricated from fibre reinforced concrete.
 27. The anchoring element according to claim 10, characterized in that the anchoring element comprises a lifting device for levelling after placement on the bottom of the body of water.
 28. The anchoring element according to claim 11, characterized in that the anchoring element comprises a lifting device for levelling after placement on the bottom of the body of water. 